LLMs Show Limited Ability to Identify Their Own Generated Code

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Researchers have investigated the ability of Large Language Models (LLMs) to recognize code they have authored, a phenomenon that could lead to unintended collusion when models are used to monitor or judge one another. A report from arXiv cs.CL details a study where models were tested zero-shot on their capacity for code attribution. The study utilized several benchmarks, including MBPP, HumanEval, and DS-1000, to see if models favor their own stylistic surface cues when acting as evaluators.

Significance of Stylistic Attribution

The research involved five commercial LLMs generating solutions for three major benchmarks, while seven additional models were tested specifically on the MBPP dataset. These models then performed four distinct tasks: choosing their own work from a pair, identifying their own work in isolation, recognizing the work of a named model, and performing blind quality assessments. The significance of this study lies in the potential for bias; if an AI can identify its own output or that of a peer, it may provide higher quality scores regardless of the actual code performance. In the task of identifying a single solution as their own, the models achieved a balanced accuracy of 49% to 58%. This range suggests that while models are not consistently accurate, they do demonstrate a measurable ability to detect stylistic markers in code.

Unknowns in Model Identification

The provided report does not specify the names of the fifteen model-benchmark combinations used, nor does it list the specific commercial models involved in the testing. Furthermore, the announcement did not specify the exact nature of the surface cues that the models use to identify their own work—whether these are related to formatting, specific commenting styles, or logic patterns. It also remains unclear how these findings might change as models become more sophisticated or if different prompting techniques could mask these stylistic signatures. The study’s full data on the blind quality task was also not detailed in the initial summary.

As the industry moves toward using LLMs for automated code review and quality assurance, these findings highlight a need for caution. Ensuring that AI judges remain objective is a growing challenge for the development of reliable autonomous programming tools.

Lead image: Lee Campbell / Pexels

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